Abstract

To achieve its full diffraction limit in the infrared, the primary mirror of the Keck telescope (now telescopes) must be properly phased: The steps or piston errors between the individual mirror segments must be reduced to less than 100 nm. We accomplish this with a wave optics variation of the Shack–Hartmann test, in which the signal is not the centroid but rather the degree of coherence of the individual subimages. Using filters with a variety of coherence lengths, we can capture segments with initial piston errors as large as ∓30 μm and reduce these to 30 nm—a dynamic range of 3 orders of magnitude. Segment aberrations contribute substantially to the residual errors of ~75 nm.

© 1998 Optical Society of America

[Optical Society of America ]

» View Full Text: Acrobat PDF (325 KB)

References

Author Affiliations

Gary Chanan, Mitchell Troy, Frank Dekens, Scott Michaels, Jerry Nelson, Terry Mast, David Kirkman

G. Chanan is with the Department of Physics and Astronomy, University of California, Irvine, California 92697 and the California Institute of Technology, 105–24, Pasadena, California 91125. M. Troy, F. Dekens, and S. Michaels are with the Department of Physics and Astronomy, University of California, Irvine, California 92697. J. Nelson and T. Mast are with the Lick Observatory, University of California, Santa Cruz, California 95064. D. Kirkman is with the Department of Physics, University of California, San Diego, California 92093.

Cited By

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.